December 2014
Intermediate to advanced
852 pages
17h 57m
English
Content preview from Joe Celko's SQL for Smarties, 5th Edition
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Chapter 23
Basic Aggregate Functions
Abstract
An aggregate function reduces a set of values to a single value. Some of the basic ones are built into SQL, and they are usually fast because optimizers and index structures often store this data for their own use.
Keywords
SUM()
AVG()
MAX()
MIN()
COUNT()
COUNT(*)
Cardinality
ALL
DISTINCT
An aggregate function reduces a set of values to a single value. Some of the basic ones are built into SQL, and they are usually fast because optimizers and index structures often store this data for their own use. The original functions are SUM(), AVG(), MAX(), MIN(), COUNT(), and COUNT(*).
Simple aggregate functions first construct a set of values as defined by the parameter. The parameter is usually a single ...
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